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Supplement Strategy: Selenium

The mineral, selenium, is a powerful antioxidant.  Additionally, research has found
other mechanisms of action of interest to breast cancer patients.

Linking Selenium and Iodine to Breast Cancer

  • Update: In 80 breast cancer patients who had a mastectomy, their blood
    levels of selenium were lower than in healthy patients.  In the patients, there
    was a significantly higher concentration of selenium in cancerous tissue, as
    opposed to adjacent healthy tissue.  The higher concentration of selenium in
    cancerous tissue may be attributable in part to selenium's defense
    mechanism (selenium activates the antioxidant glutathione) against the
    carcinogenic process. (See Charalabopoulos K et al., Selenium in Serum
    and Neoplastic Tissue in Breast Cancer: Correlation with CEA, bjcancer
    2006.)

  • Selenium helps to convert T(4) - thyroxine, the prohormone with 4 molecules
    of iodine into T(3) - triiodothyrone, the cellularly active thyroid hormone, with
    three molecules of iodine.  Thyroid hormones help the entire body - raising
    the metabolic rate and balancing physiological functions.

  • Selenium is an antioxidant, a part of glutathione peroxidase, which prevents
    fats from being oxidized.  During the production of thyroid hormones,
    selenium helps to degrade excess hydrogen peroxide that can damage the
    cells.

Selenium Reverses Chromosome Breaks

UPDATE:  Selenium has several anticancer properties, including protection against
oxidation and enhancing nucleotide excision repair.

Women who carry a mutation of the BRCA1  gene were found to have more
chromosome breaks ( which can lead to breast cancer ) than women who did not
carry the mutation.
 When women with the BRCA1 mutation were given selenium
for three months, the number of their chromosome breaks were reduced to
normal.

(See Kowalska E et al., Increased Rates of Chromosomes Breakage in BRCA1
Carriers are Normalized by Oral Selenium Supplementation, Cancer Epidemiology
Biomarkers and Prevention 2005. See also Alternative Medicine Magazine, March
2006.)

Double-Blind, Placebo-Controlled Cancer Study

Although there have been many studies on selenium, we include it on the list of
beneficial supplements for cancer principally because of the following double-blind,
placebo-controlled study published in JAMA.

Selenium supplements can reduce cancer rates, new study shows

Jan. 7, 1997 Press release

ITHACA, N.Y. -- Men and women taking selenium supplements for 10 years had 41
percent less total cancer than those taking a placebo, a new study by Cornell
University and the University of Arizona shows. "Although more than a hundred of
animal and dozens of epidemiological studies have linked high selenium status
and cancer risk, this is the first double-blind, placebo-controlled cancer prevention
study with humans that directly supports the thesis that a nutritional supplement of
selenium, as a single agent, can reduce the risk of cancer," said Gerald F. Combs
Jr., a nutritional biochemist and Cornell professor of nutritional sciences.

Combs and a group of co-authors reported their findings in the Jan. 1, 1997 issue of
The Journal of the American Medical Association.
The senior author is
epidemiologist Larry Clark, who was at Cornell at the onset of the study and is now
at the Department of Family and Community Medicine at the University of Arizona
School of Medicine.

In 1983, the researchers recruited 1,312 randomized patients with histories of skin
cancer at seven dermatology clinics located in low-selenium areas of the United
States (Augusta and Macon, Ga., Columbia, S.C., Wilson and Greenville, S.C.,
Miami, and Newington, Conn., where consumers ingest an average of about 100
micrograms of selenium a day). The patients were given either a placebo or a 200-
microgram daily supplement of selenium (twice the average amount these
Americans consume in their diet, thereby tripling their selenium intake).

Skin cancer patients were chosen because they have a 25 percent annual chance of
a recurrence, and skin cancer is easy to diagnose and can be quickly treated. The
researchers set out to determine whether they could reduce the average recurrence
rate with selenium supplements.

Ironically, 10 years later, the results were not significant for skin cancer. However,
they were "compelling" for overall cancer incidence and mortality rates, Combs
stressed. Of the selenium group, 69 developed some type of cancer compared with
116 of the placebo group; 28 of the selenium patients died of cancer compared with
58 from the placebo group.

"Overall, the selenium group experienced 18 percent less mortality than the
placebo group, and almost all of that difference was due to some form of
cancer,"
said Combs, who credits Cornell with having the longest history of
research in selenium nutrition research in the world.
"This is the first time anyone
has shown that any single nutrient can result in such a reduction in cancer risk
.
The fact that we saw a pattern in lower incidence and mortality rates across all the
clinics gives us even greater confidence in these findings."

Prostate, esophageal, colorectal and lung cancer rates were among the most
dramatic: patients in the selenium group had 71 percent, 67 percent, 62 and 46
percent reductions in cancer rates, respectively, than the placebo group.

The current Dietary Guidelines now recommend that men consume 70 micrograms
of selenium a day and women 55 micrograms; Americans typically get between 100
to 160 micrograms a day in their diets, Combs said.

Selenium blood levels vary widely in populations. Even Americans with the lowest
selenium intake of 60 to 80 micrograms per day -- those living along the
Southeastern seaboard and in the Pacific Northwest -- ingest two to five times more
than citizens of New Zealand and 10 to 20 times more than people living in some
areas of China. Selenium blood levels vary among populations largely because of
wide differences in soil, agronomic practices, food availability and preferences and
methods of food preparation.

Although a 1995 Harvard University study of more than 62,000 nurses reported no
anti-cancer benefits of selenium, Combs said that the researchers measured
selenium in the toenail clippings of the nurses. "This method presumes that the
concentration of selenium in nails accurately correlates with metabolic selenium
status in the body," Combs pointed out. "There is no evidence for that."

The University of Arizona-Cornell research team reported in 1991 that low selenium
levels in the blood were linked to increased risk of neoplastic polyps in the colon, a
precursor to colorectal cancer. And in other studies at Cornell, colleagues of Combs'
reported in 1995 that animals fed diets high in selenium had 50 percent fewer
tumors than those fed diets of average selenium content.

Combs is not recommending the use of oral supplements of selenium; however, he
does emphasize the importance of consuming low-fat diets that are adequate in
selenium and are balanced with respect to other essential nutrients. The most
important dietary sources of selenium are meats, fish and cereals; dairy products
and eggs contribute significant amounts. Some nuts can also be high in selenium if
they were grown in high-selenium areas.

Of the 40 nutrients currently recognized as essential for human nutrition, selenium
was the last to be recognized in 1957. A key component for at least two essential
enzymes, selenium provides the body with antioxidant protection in concert with
vitamin E and is required for normal thyroid hormone metabolism.

The study was funded in part by grants from the American Institute of Cancer
Research, the American Cancer Society and the National Institutes of Health.

Editor's note: the usual recommended selenium dose is
    200 mcg. Selenium works synergistically with iodine.

The statements above have not been evaluated by the U.S. Food & Drug
Administration.  The supplements discussed are not intended to diagnose, treat,
cure, or prevent any disease.

This website is intended as information only. The editors of this site are not medically-trained.
Please consult your licensed health care practitioner before implementing any health strategy.
The information provided on this site is designed to support, not replace, the relationship that
exists between a patient/site visitor and his/her existing physician. This site accepts no
advertising. The contents of this site are copyrighted 2006 by Breast Cancer Choices, Inc.
Contact us for reprint permission.

Website updated January  7, 2008
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